The present invention generally relates to machine pallet systems and, more specifically, to a remote controlled indexer system and method for machining a part surface.
Most conventional machined part surfaces are oriented to a spindle and cutter by fixturing, while the surfaces are generated by a side or end of the cutter. Occasionally a surface cannot be orientated perpendicular or parallel to the spindle without re-fixturing, so the surface is generated by a technique called hemstitching. Hemstitching involves moving a ball type cutter across a surface with passes so close that the surface appears to be smooth. This technique could require hundreds of cutter paths (instead of just a few) costing hours of valuable machine time. Although hemstitching can produce angled surfaces, there are occasions where the part must be rotated to access features to be generated on the part. This would require additional fixturing and repositioning on a machine that does not have enough axes to orientate the part to the desired position. This is not cost effective when a factory can produce over a thousand different part types on a single machining center with less than fifty fixture pallets available to use.
Another common alternative is for the factory to put these parts on their 5-axis palletized machines. These palletized machines typically have a work envelope of approximately 1 cubic meter or larger and are typically reserved for heavy complex machining on large parts due to the expense of the palletized machines, and the high cost of operating them. Some 5-axis machines are dedicated to build parts that could fit in a 6″ cube and weigh about 6 oz. This is not the best use of the palletized machines but it is currently the best option because of machine capacity issues in other areas.
There are instances where many parts could be machined more cost effectively on 5-axis palletized machines than on 4-axis palletized machines. However, 5-axis machines are more expensive and require more maintenance. Several small parts on a 5-axis machine could be formed using a 4-axis machine if a 5th axis rotary table was added. The rotary table would enable a spindle (in a factory machining center) to be perpendicular or parallel to the part, which is the optimal condition for milling.
There are several multi-axis devices available to resolve these problems, but most are hard wired to the palletized machine, or are limited by their positioning ability. This prevents an automated pallet shuttle system in the factory from moving pallets in and out of the machine. The most common type of multi-axis device uses the same power source as the palletized machining center and is wired directly to a machine controller. This common multi-axis device typically works in conjunction with the other axes in the palletized machine to produce full contouring capabilities. Another device is available that can position the part for cutting. This other device is a mechanical device that is operated by either the rotation of a spindle in the machining center, or the spindle holding a device that can “push into” the axis for a ratcheting effect. The accuracy, reliability, and functionality of these mechanical devices are claimed to be very poor, and interrupt the automated machining process.
If a remote controlled multi-axis device were available, an option of cutting these parts on lower cost 4 axis machines rather than 5 axis machines would exist. This would allow the factory to move the parts to different machine types depending on the current workloads for the machines.
As can be seen, there is a need for adding an additional axis onto a machine pallet, to enable the machine pallet to be shuttled through a pallet handling system and into a machining center without making additional connections.